报告摘要：A dark matter halo has traditionally been viewed as a virialized structure bounded by its virial radius. However, the growth of a halo means it is inevitably surrounded by a non-virialized envelope of freshly accreted material. Failing to account for this envelope has led to major difficulties in the classical halo model, while a number of recent works have attempted to solve the problems by redefining the halo with new boundaries.

In this talk I will report our recent development of the depletion radius, which is a highly competitive new halo boundary stemming from the macroscopic physics of halo growth. I will show that the depletion radius is both an important physical probe for halo evolution and a concise geometric boundary for halo models of the large scale structure, capable of overcoming major limitations of the classical halo in a systematic way. I will also present our observational measurements of the depletion radius for both our Milky Way halo and DESI galaxy groups.

主讲人简介：Jiaxin Han got his PhD from Shanghai Astronomical Observatory in 2013 and subsequently worked as postdocs at the Institute for Computational Cosmology (Durham University, UK) and Kavli IPMU(Tokyo University, Japan), before joining Shanghai Jiao Tong University in 2018 as a faculty member. His research focuses on computational and observational studies of the dark matter distribution. He has been supported by the Marie-Curie foundation (EU), JSPS (Japan) and the national talent recruitment program (China) among others.